Railway signaling apparatus



April 15, 1930. c, R BEALL 1,754,592

RAILWAY SIGNALING APPARATUS Filed Jan. 11, 1928 E i 2 i2 2 .INVENTOR I C. Bed/l bpcmu'zz Patented A r. 15, 1930 UNITED\ STATES PATENT OlfFICE CHARLES R. BEALL, OF IDQEWOOD BOROUGH, PENNSYLVANIA, AS SIGNOB TO m UNION'SWI'IGE SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPOBA- TION OI PENNSYLVANIA Runway srenanmo arra'narus Application Med January 11, 1928. Serial No. 245,890.

My invention relates to railway signaling apparatus, and particularly to apparatus of the type involving track circuits.

The present case is a continuation in part of my co-pending application, Serial No.

126,969, filed August 4, 1926,'for railway signaling apparatus, in so far as the subject matter common to the two cases is concerned.'.

I will describe two forms of apparatus em bodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 is a similar view showing a modified form of the apparatus illustrated in Fig. 1 and also embodying my invention.

Similar reference characters refer to similar parts in both views.

Referring first to Fig. 1, the reference characters 1 and 1 designate the rails of a railway track, which rails are divided by insulated joints 2 to form a section E-F. This section is provided with a track circuit comprising a transformer T having its secondary 10 connected across the rails adjacent the point F, and atrack relay R connected across the rails adjacent the point E. The primary of the transformer T is constantly energized from a source of alternating current not shown in the drawing.

Interposed between the secondary 10 of transformer T and the track rail 1 is the primary 5 of a transformer C, the secondary i5 4 of which is connectedwith the mid point of an impedance A and with an auxiliary conductor B. The impedance A is connected across the track rails 1 and 1 of the section EF, and the auxiliaryconductor B is in contact with the track ballast. This conductor B is preferably located midway between the rails 1 and 1", and may, for example, be sp iixed to the usual ties which support these ra1 s.

As is well understood in the, railway sigconstant regardless of weather conditions.

naling art, the ballast leakage resistance of a track section, that is, the resistance from rail to rail through ties and the ballast, va-.

ries through wide limits, depending on weather conditions. When the ballast is wet 5o this leakage resistance is comparatively low, but when the ballast is dry the leakage resistance is comparatively high. It follows that with a substantially constant voltage across the primary of transformer T, if transformer C were not included in the track circuit, the voltage across the rails adjacent relay B would be larger when the ballast resistance is high' than when the ballast resistance is low. The voltage applied to relay R would, therefore, vary in accordance with the condition of the ballast. I Considering the transformer C, when the ballast resistance is high, the secondary 4 of this transformer is practically on open circuit, so that only a small current will flow therein, and the rimary 5 of this transformer will, there ore, ofi'er considerable impedance to the flow of current from the secondary of the track transformer T to the track rails, and'the energy supplied to the track rails will, therefore, be relatively low. In wet weather, however, the resistance between the rails and the conductor B will be relatively low, so that the resistance in cir-- cuit with the secondary 4 of transformer C will be relatively low, and this transformer will then offer a lower impedance to the flow of current from the track transformer T to the track rails, with the result that the energy iupplied to the track rails will be relatively l t will be seen, therefore, that the voltage applied to relay R may be made substantially Furthermore, the phase relation of the current in the track rails with respect to the current in the primary of transformer T is varied in response to variations in weather conditions, l. eing of a relatively low power factor in dry weather and of a relativelyhi h ower factor in wet weather, so thatif the re ay is of the two-winding type the phase angle between the currents in its windings 7 and 9 will increase as the ballast resistance decreases. This feature tends to further compensate for variations in the resistance of the ballast, and so to prevent variations in the torque applied to the relay.

If the core 3 of transformer C were a closed magnetic circuit, the power factor of the pnmary circuit of this transformer would be relatively high, but this would be undesirable because the power factor of the track circuit should be low in order to provide the proper phase displacement of the current in the two windings of the relay B. To produce a low power factor, I provide an air gap 6 in core 3. I also preferably provide a magnetizable member 8 in shunt to that portion of core 3 which includes the air gap and carries the secondary 4, so that by adjusting the I position of member 8 with respect to the core 3 I can vary the effect of the air gap and of the regulating coil 4 and thus vary the power factor of the track circuit for any given ballast resistance.

Referrin now to Fig. 2, the reference character designates a reactor comprising two magnetizable cores 22 and 23. Core 22 is provided with two windings 11 and 18, while core 23 is provided with two similar windings 12 and 19. Windings 11 and 12 are connected in series between the secondary 10 of transformer T and the rail 1 of section E-F.

The reference character D designates a full wave rectifier which is provided with alternatin current input terminals 13 and 14 connecte directly w1tha secondary 12 of transformer T The rectifier D is also provided with direct current output terminals 15 and 16. Terminal 15 is connected with auxiliary conductor B by wire 21. Terminal 16 is connected to an intermediate point on reactance A through wire 17, windings 18 and 19 in series, and wire 20. It will therefore be seen that unidirectional current from the rectifier D flows through windings 18 and 19 in series with a ortion of the track ballast. Any variation in the resistance of this ballast will therefore vary the magnitude of the current in the windings 18 and 19, the current increasing with decrease in ballast resistance. But the current in windings 18 and 19 creates unidirectional fluxes in cores 22 and 23 respectively, the parts being so proportioned that when the ballast resistance is comparatively high, the comparatively small current than flowing in windings 18 and 19 magnetizes the cores 22 and 23, respectively, to comparatively low flux densities which are preferably greater than the flux densities corresponding to the maximum permeability of the cores. If, now, the ballast resistance decreases, as in wet weather, the current flowing in windings 18 and 19 increases.- The re-' sulting increase in the flux through cores 22 and 23 causes the permeabilities of the cores to decrease. The effective total reactance of windings 11 and 12, carried by the cores 22 flowing through windings 11 and 12 in series,

creates alternating fluxes in the cores 22 and 23, which fluxes in turn induce alternating electromotive forces in windings 18 and 19. But it is undesirable to have alternating current flowing in the circuit including windings 18 and 19. I therefore prefer to connect windings 18 and 19 in series 0 position, and to proportion the parts in suc manner that the alternating electromotive forces induced in these windings are substantially equal. With this arrangement it will be seen that the alternating electromotive force induced in winding 18 by alternating current in winding 11 will be neutralized by the alternating electromotive force induced in winding 19 by alternating current in winding 12.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the a pended claims without departing from t e spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a signal system involving a section of railway track having a source of track circuit voltage connected with the rails of the section, an auxiliary conductor in contact with the track ballast, and a transformer having its primary inter osed between said source and one of the trac rails, and the terminals of its secondary connected with said conductor and a track rail.

2. In a signal system involving a section of railway track having a source of track circuit voltage connected with the rails of said section, an auxiliary conductor in contact with the track ballast, anjmpedance connected across the rails of said section, and a transformer having its rimary interposed between said source and one of the track rails and the terminals of its secondary connected with said conductor and with an intermediate point in said impedance.

3. In a signal system involving a section of railway track having a source of track cirwith the track ballast, a coil interposed between said source and one of the track rails, and means responsive to variations in; the resistance of the track. ballast between said auxiliary contact and a track rail for varying the effective reactance of said coil.

4. In a signal system involvin asection of railway track and a source 0 track c1rw cuit voltage connected with the rails of said section, a transformer having its primary interposed between said source and one of the track rails, and m ans for varying the resistance between the terminals of the secondary of said transformer, in response to:

variations in ballast resistance.

5. In a signal system involving a section of railway track and a source of track circuit voltage connected with the rails of the section, a magnetizable core provided with a first winding connected inseries with said source, and a second winding supplied with unidirectional current the magnitude of which varies in response to variations in'the resistance of the track ballast. I

6. In a signal system involving a section of railway track and a source of track circuit voltage connected with the rails of the section, a magnetizable core, a first winding on said core inter osed between said source and one of the trac rails, and a sec ond winding located in inductive relation with the first winding and supplied with a unidirectional current for varying the effective reactance of said first winding in response to variations in the resistance of the track ballast.

7. In a signal system involving a section of railway track and a source of track circuit voltageconnected with the rails of said section, a magnetizable core, a first winding on said'core, means for supplying said first winding with current the magnitude of which decreases in accordance with increases in the ballast resistance but which is sufiicient when the ballast resistance is comparatively large to cause a flux density in said core greater than that corresponding to the maximum permeability of the core, and a second winding on said core interposed between said source and one rail of the section and having an effective reactance which depends on the permeability of the core. I

8. In a signal system involving a section of railway track and a source of track circuit voltage connected with the rails of the section, an auxiliary conductor in contact with the track ballast, an impedance connected across the rails of said section, a magnetizable core, a first winding carriedby said core and interposed between said source and one of the track rails, a second winding in inductive relation with said first winding, a source of unidirectional current, and means lncluding said second winding for connecting sald source between saidauxiliary conductor and an intermed1ate point of said impedance.

9. In combination with a section of railway track, two magneti'zable cores, a first and second wlnding on-one core, a third and fourth wmding on the other core, means for supplying said second and third windingsin serles.

with a unidirectional current which varies 1n accordance with variations in the resistance of the track ballast, and means for-supplying alternating current to the rails of said section in series with said first and fourth winding in such manner that the alternating electromotive force induced in the second winding by such alternating current in the firstwinding is neutralized by the alternating electromoa tive force induced in the third winding by such current in the fourth winding.

10. In a signal system involving a section ofrailway track and a first source of track circuit voltage connected with the rails of the section, an auxiliary conductor in. contact with the track ballast, an impedance connected across the rails of the section, a magnetizable core, a first winding on said core interposed between said source and one of the rails, a second winding on said core, a second source of voltage, and means including said second winding for connecting said second source between said auxiliary conductor and twintermediate point of said impedance.

11. In a signal system involving a section a of railway track and a source of track circuit voltage connected with the .rails of the section, an auxiliary conductor in contact with the track ballast, a magnetizable core, a first winding on said core interposed between said source and one of the track rails, a second winding on said core, a source of unidirectional current, and means including said second winding for connecting said source of unidirectional current between said auxiliary conductor and an intermediate point on said impedance. 12. In combination with a section of railway track, a first source of voltage connected with the rails of the section, a magnetizable core, a first winding on the core, a second source of voltage, means for connecting the second source in series with the first winding and a portion of the track ballast, and a second Winding on the core interposed between said first source and one rail of the section and having an efl ective reactance which depends upon the magnetization of the core.v

13. In combination with a section of railway track, two magnetizable cores, a first and and means for supplying alternatingcurrent to the rails of said section in series with said first and fourth winding in such manner that the alternating electromotive force induced in theisecond winding by such alternating current in the first winding is neutralized by the alternating electromotive force induced in the third winding by such current in the fourth winding.

In testimony whereof I afiix my signature.

CHARLES R. BEALL. 

